This grant application requests support for a new training program in Environmental Life Course Epidemiology. The training program will be directed by Drs. Pam Factor-Litvak and Robin Whyatt. It requests funds for two pre-doctoral trainees and one post-doctoral trainee in year 1, and gradually increases to a total of four pre doctoral and two post-doctoral trainees by year 5. The proposed mentors are well funded and well published investigators with considerable experience in training Master's, pre-doctoral and post-doctoral students. The theme of the program is to train a new generation of scientists in the life course approach to environmental epidemiology and population health that is to investigate early environmental exposures and outcomes which may not manifest themselves until later in the life course and to study the possible biologic, social, behavioral and psychological mechanisms behind such exposure - outcome relationships. The proposed program builds upon the long, distinguished and ongoing history of life course and molecular epidemiology approaches at Columbia. Pre doctoral trainees will complete the requirements for a PhD in epidemiology or environmental health sciences, including specific course requirements in the life course track and dissertation research related to the life course, and will be offered funding for a period of 5 years. Post-doctoral trainees will pursue research in environmental life course epidemiology under the guidance of experienced mentors. Thus, trainees will be uniquely prepared to perform environmental life course research in a variety of academic and public health settings.